Apparatus for testing the point bearing capacity of a driven pile shell



APPARATUS FOR TESTING THE POINT BEARING CAPACITY OF A DRIVEN FILE SHELLE. D. WATT Aug. 4, 1936.

Original Filed April 5, 1955 2 Sheel'xs-Sheetl l INVENTOR. EZ/Lu/ 0; WQ

/J/f ATTORNEYS.

Aug. 4, 1936. E. D. WATT APPARATUS FOR TESTING THE POINT BEARINGCAPACITY OF A DRIVEN PILE SHELL 2 Sheets-l-Sheet 2 Original Filed April5, 1935 0 m w 4 y h y I .a I II t m I, 7 O 7 A q A a O 4 o 8 3 a 2 9 a 2M, a 4 3 l u w w `m w \V\\\\\\*\\ \\V g/) \\\\\\\\\\\N\\\\\\\\\\\\\\\\\W W 0 lNvENToR. Ehh@ Wal/ ATTO EN EY'.

Patented Aug. 4, 1936 pairs!) STT-iras PATE NT LFIIC E APPARATUS FoaTESTING TII-E POINT BEARING oAPAcrTY oF A DRIVEN PILE SHELL @riginalapplication April 5, 1933,"Seral No.

Divided and this application August 3i, i934, Serial No. '742,457

8 Claims.

This application is a division of my co-pending application, Serial No.664,517, and pertains to the manufacture of concrete piles in which thethin, comparatively delicate shell used as a permanent mold for theconcrete is surrounded and protected during the driving operation by aheavy tubular casing which is subsequently removed.

An object of the present invention is to disclose apparatus for testingthe point resistance of the shell after driving, and prior to filling itwith concrete.

Further and other objects and advantages Will be apparent from thespecification and claims, and from the accompanying drawings Vwhichillustrate what is now considered the preferred embodiment of theinvention.

Fig. l shows a shell casing and driving core at conclusion of thedriving operation, the v'driving core being provided With a drop hammerwithin its lower end.

Figs. 2 and 3 show modifications of the lower end of Fig. l.

Fig. 4 is a view similar to Fig. 1, but with a hydraulic plunger in thedriving core in place of the drop hammer.

Fig.5 lshows a modification of the lower end of Fig. 4.

Thepile shell, designated 28, is provided at its lovver end with aWelded-on sheet steel boot 22, and the casing is'designated 28. Thecasing is provided at its upper end with a ring 38 having hooks 82adapted for engagement by links 34 hanging from the drive head. Duringthe driving operation collar 36 is in Contact with the under surface ofthe drive head and after the driving is finished, hooks 32 serve asconvenient means for engaging the casing to Withdraw it from itsposition about the shell.

Boot 22 is provided near its top with a circumferential bead 33 andabove the bead is an angle ring i6 fitted as shown snugly around the topof the boot. The bottom of casing 28 engages ring 46 as shown and thering serves during driving to prevent entrance of material betweencasing and shell. Also, during driving, ring 4i! serves as a plow inadvance of the casing.

After the driving operation is iinished, the drive core and casing maybe withdrawn, leaving shell 26, boot 22 and ring 46 in place. Duringwithdrawal, any attempt of shell 26 to follow the casing and core isusually prevented by engagement of the surrounding earth with ring 46,which in turn engages bead 38 on the boot.

During the driving of a pile shell by the method described above, twokinds of resistance are encountered, one being the friction of thecasing, and thev other being the pointbearing or resistance of theAboot, or bottom of the shell. After the pile isy completed, the carryingcapacity represented by the point bearing remainsjbutfthe friction ofthefground on the sides of thepile may be largely-lost, due tothefact-'that the Withdrawal of the casing leaves a void between shell`vand ground, and the void may not completely applying a knovvnforce tothe boot/'afterit is1 driven. One method is shown in Figs.-1, 2 and 3,in which a drop hammer; 58'is inserted in the bottom part of the driveVcore 52, the -.top of the hammer contacting with'shoulde'r 54 ofthecore. After the driving operation is nished, the core is raised possiblytwo or three feet and the hammer is operated .by means of cabley 56passing over 'sheave'58 in drive head' 59, the' driving core actingv asa guide for the hammer. If the bearing capacity of the pointbe foundinsuiiicient, the drop hammerj may be loperated until suitable'carrying' capacity is obtained. VThe' drop hammer Ymay also be usedto'assist in holdingU down the shell during Withdrawal of core andcasing. The

Jharn'm'eris"`iinall'y withdrawn' by its cable' 56.

Fig. 1 shows both drop weight and core in contact with boot 22, thuspermitting the hammer to contact with a very limited area of the boot.

Fig. 2 shows a modicaion permitting greater contact between hammer andboot. Shell and boot 60 are attached to a step ring 62, and the hammer64 is so shaped as to bear on the step ring as Well as on the innersurface of boot 60. During the driving operation core 66 is raised toserve as a guide for the hammer.

Fig. 3 shows a modification in which an anvil 68 remains in contact withboot 60 and step ring 62, the anvil being driven by hammer 10. The anvilis connected to the hammer by a pin 12 having a head 14 with which splitcollar 16 (fast in the hammer) engages when the hammer is raised out ofthe shell.

Figs. 4 and 5 show the use of a hydraulic plunger to test the pointbearing capacity of the pile and also to lift the core and casing byreaction against the point of the shell. During the driving operationthe parts are assembled as in Fig. 4, shell 20, boot 22, casing 28, bead38 and angle ring 40 being the same as before. In this modication,however, the drive core 80 is bored to receive a plunger 82 adapted tobe forced downwardly relatively to the core when fluid under pressure isadmitted to space 84 between plunger 82 and drive head 86. Forconvenience, plunger 82 is usualy hollow, and its lower end has a head88 seating in concrete 90 with which boot 22 is filled (Fig. 4). Amodfied arrangement of plunger head is shown in Fig. 5, in which noconcrete is used in the boot, Contact being made directly with the bootby a suitably shaped head 92.

After driving, fluid is forced through passage 95 into space 84. Thisfluid tends to lift the core and casing and to force the shell furtherinto the ground. If the friction between ground and casing, aided by aload placed on drive head 86, is sufficient, the force acting downwardlyon the point will be sufficient to impose a satisfactory test load (asmeasured by a pressure gauge) on the pile point. If the point resistanceis below requirements, the shell can be pushed down by the plunger untilsuicient point resistance is obtained. Core and casing. are finallyraised by still further increasing the uid pressure or by removing loadfrom the drive head, or both. This reaction arrangement eliminates allpossibility of the shell rising while core and casing are beingwithdrawn.

The plunger is withdrawn into the core by cable 94 passing between shell20 and core 88 through a passage in head 88 or 92 and over sheaves 96 indrive head 86.

It is to be understood that the invention is not limited to the specificembodiments herein illustrated and described, but may be used in otherways without departure from its spirit as dened by the following claims.

I claim:-

1. Apparatus for testing the point bearing capacity of a driven pileshell having a boot, comprising in combination, means for applying aknown downward pressure on said boot, and means for preventing contactof the shell with the surrounding ground while said downward pressure isbeing applied.

2. Apparatus for testing the point bearing capacity of a driven pileshell having a boot, comprising in combination, means for hammeringdownwardly with known force on the inside of the boot, and means forpreventing contact of the shell with the surrounding ground while saidhammering is taking place.

3. Apparatus for testing the point bearing capacity of a driven pileshell having a boot, cornprising in combination, a drive core within theshell, a drop hammer in said core, a casing surrounding the shell, andmeans for dropping said hammer onto the inside of said boot.

4. Apparatus for testing the point bearing capacity of a driven pileshell having a boot, comprising in combination, a hammer within theshell, guide means for said hammer, a casing surrounding said shell toprevent contact of the shell with the ground, and means for applyingsaid hammer to the inside of said boot.

5. Apparatus for testing the point bearing capacity of a driven pileshell having a boot, comprising in combination, a drop hammer within theshell, a drive core within the shell and serving to guide said hammer, acasing surrounding said shell, and a cable attached to said hammer andpassing upwardly through said drive core whereby said hammer is appliedto the inside of said boot.

6. Apparatus for testing the point bearing capacity of a driven pileshell having a boot, comprising in combination, hydraulic pressure meansfor pressing downwardly on the inside of said boot, and a casingsurrounding the shell to prevent contact of the shell with the groundwhile the pressing operation is taking place.

'.7. Apparatus for testing the point bearing capacity of a driven pileshell having a boot, comprising in combination, a drive core within theshell, a plunger slidable vertically in said core, a casing for keepingthe exterior of said shell out of contact with the ground, said plungerbeing adapted to be pushed by iiuid pressure downwardly against theinside of the boot.

8. Apparatus for testing the point bearing capacity of a driven pileshell having a boot, comprising in combination, a drive core within theshell, a plunger slidable vertically in said core, a casing for keepingthe exterior of said shell out of contact with the ground, said plungerbeing adapted to be pushed by fluid pressure downwardly against theinside of the boot, and cable means for withdrawing said plungerupwardly into said core.

ELIHU D. WATT.

